Many of the proteins involved in DNA replication and recombination in both prokaryotes and eukaryotes have been defined. Considerable conservation of these events has been noted over great evolutionary changes. In eukaryotes, origin activation has been shown to involve the origin recognition complex and a battery of other critical proteins that interact with the complex. In recombination, key steps in this process involve formation and processing of intermediates and resolution of joined molecules. The precise manner by which replication and recombination are initiated and subsequently controlled, however, remain unclear, as is the function of many of the key gene products. Furthermore, the realization that replication and recombination can be coupled has recently become evident, but the precise nature of that coordination is unknown. The goal of the meeting is to bring together investigators pursuing these problems at all levels (involving biochemistry, genetics and biophysics) to discuss recent advances. Such an exchange of information will permit an in depth evaluation of new directions that should prove fruitful for future research efforts. The Keystone Meeting on the Mechanism of DNA Replication and Recombination has been held every three years. It is the only meeting that is held which brings together scientists that share these common interests.